Various designs of valves for operating and controlling the flow of water from domestic water faucets have been implemented through the years. In one common valve design, a threaded valve stem is configured to be manually treaded into and out of a valve body. The interior end of the valve stem is provided with a replacable rubber washer or pad that is driven into sealing engagement with the mouth of a water supply passageway when the valve stem is threaded into the valve body. This functions to shut off the flow of water through the valve and thus turns off the faucet. When the valve stem is threaded out of the valve body, the washer is drawn progressively away from the mouth of the passageway allowing water to flow through the faucet. The magnitude of the flow is determined by the distance between the washer and the passageway mouth. Thus, the flow rate from the faucet is controlled by threading the valve stem out of the valve body until the desired flow rate is achieved. These types of faucet valves are used extensively in kitchen, bathroom, and garden faucets and usually are made of brass that can be plated with, for example, a nickel alloy. In addition, faucets for use in kitchens and baths are often provided with auxiliary aerators at the faucet tip for regulating the flow of water to a predetermined maximum rate. This is because the natural flow rate that results when the valve is opened usually is too strong for the purposes of such faucets.
Another type of valve typical in domestic faucets includes a ball that fits within a socket through which hot and cold water supply passageways extend. The ball has one or more openings that communicate with the spigot of the faucet. A handle extending outwardly from the faucet can be used to control the position of the ball within the socket to align or misalign the openings in the ball with those in the socket. When the openings are aligned, water flows through the ball and through the spigot. When the openings are misaligned, the ball functions to prevent flow and the faucet is off. A user can manipulate the handle to achieve a desired flow rate and to select a desired water temperature through appropriate mixing of water from the hot and the cold water supplies. In most cases, these types of faucets are also fabricated of brass, plated brass, or other appropriate metal, although in some instances the ball portion of the valve is fabricated of a plastic material and the ball is replaceable. In most cases, these faucets are also provided with aerators at the ends of their spigots to regulate the flow of water to a usable rate.
While these common types of faucet valves have proven successful for kitchen and bathroom faucets, they are not particularly suited to use in drinking water faucets that dispense purified, filtered, and/or distilled water for drinking and cooking. In such faucets, a multi-turn threaded stem type valve is cumbersome to use because water usually is drawn from the faucet in numerous brief bursts to fill glasses or pans that are held in one hand of a user. Further, there generally is no need to have the degree of control over the flow rate that is provided by these multi-turn valves. Instead, it is preferred that the faucet simply be turned on and off quickly, easily, and conveniently. Finally, where distilled or purified water is being dispensed for drinking, the rubber pads or washers of multi-turn valves are highly undesirable because they can degrade over time and can impart impurities to the water as it flows through the valve. Metal components of the valve can also leach metals and metal oxides into the water. For many of these same reasons, ball and socket type valves also are unsuited to use in purified drinking water faucets.
Valves specifically designed for use in purified drinking water faucets have been developed. One such valve, commonly known as a push button valve, can be opened and closed by pressing and releasing a lever attached to the valve. When the lever is pressed, it depresses a spring biased plunger into the valve body and this, in turn, moves a washer or pad away from the mouth of the water supply passageway to permit the flow of water through the faucet. While such a valve is convenient, it nevertheless embodies certain inherent shortcomings. In particular, the push button valve still operates with a rubber or synthetic pad that can leach contaminants into the purified water. Further, metal components such as the plunger and particularly the spring for biasing the plunger are still required. Such metal components, even where plated with a nickel or other alloy are highly undesirable in purified water faucets because purified and distilled water, unlike ordinary tap water, is particularly corrosive to metals. When purified or distilled water contacts a metal surface, the metal is slowly broken down and the metal molecules and oxides of the metal become dissolved in the water. Thus, not only does the water become contaminated with unwanted metals and metal oxides, the metal itself is dissolved over time and eventually must be replaced. This can be a particularly acute problem during long periods of non-use when water within the faucet and valve is subject to prolonged contact with the metal components of the valve.
Another type of valve developed for use with purified water dispensers is the quarter-turn rotary valve. In this valve, a pair of small stacked ceramic discs are positioned in the water passageway of the valve. Each disc has a pair of opposed radially extending wing-shaped openings formed through the disc. In one rotary position relative to each other, the openings in the discs align to allow water to flow through the discs and be dispensed from the faucet. However, when one of the discs is rotated ninety degrees relative to the other disc, the openings misalign and communication through the faucet is cut off. A rotatable valve stem extends into the valve and is operatively coupled to one of the discs to rotate it with respect to the other disc. The valve stem is provided with a knob that can be manually rotated through ninety degrees (thus the term "quarter turn" valve) to open up and close off the valve.
Such quarter turn rotary valves are an improvement over conventional valves and push button valves. However, they too have their problems. The bodies of these valves have been made of metal such as brass. In addition, the valve stem and other components of the valve have also been fabricated of metal. As discussed above, this poses a serious problem when dispensing purified or distilled water because the metal tends to dissolve or leach into the water, which contaminates the water and wears away the metal parts.
To combat the problem of metal corrosion, metal parts are sometimes plated with nickel or nickel chromium compounds. While this helps, it nevertheless does not solve the problems associated with metal valve parts. Further, fabricating valve parts of metal and plated metal is an expensive and time consuming process. Finally, these prior art quarter turn valves typically have had no means of limiting the flow of water through the valve to a rate less than that naturally provided by the size of the openings in the ceramic discs of the valve. Accordingly, auxiliary aerators or other means of limiting flow rate have been employed for this purpose.
Accordingly, there exists a need for an improved valve for use in purified drinking water faucets that does not leach metals or other compounds into the water, that is convenient and quick to use, and that includes built in self regulation of water flow rate for eliminating the need for auxiliary aerators or other regulators. Such a valve should be durable, and should withstand the torque and tensile forces imparted to it when it is installed in the base of a dispenser faucet. It is to the provision of such a valve that the present invention is primarily directed.